Polyurethanes are a versatile class of polymers which find applications in elastomers, foams, coating, biomedical devices, etc. The principal monomers for synthesis of polyurethanes are diol/polyol and diisocyanates. Usually, hydroxyl-terminated prepolymers or aliphatic diols and diisocyanates such as toluenediisocyanate, methylene bis(phenyl isocyanate), hexamethylene diisocyanate, etc are used. The starting materials for synthesis of polyurethanes are mostly derived from fossil resources. Recent research efforts are directed towards synthesis of diols/polyols and diisocyanates based on renewable resource materials. Several examples of diols/polyols and aliphatic diisocyanates derived from bio-based chemicals are known in the literature. However, examples of aromatic diisocyanates based on bio-derived chemicals are scarce. Still et al. in Macromolecular Chemistry and Physics, Volume 185, Pages 697-707, Journal 1984 disclose synthesis of renewable furan-based diisocyanate.
Lignin is one of the most abundant aromatic renewable resource and is a by-product of various industries like sugarcane industry, paper and pulp mills. Utilization of lignin-based aromatic building blocks for the synthesis of monomers is of great interest. Recently, Pang et al. in Polymer Chemistry. Volume 5, Page 2843, Journal 2014 reported aliphatic-aromatic polyesters from lignin-derived chemicals. Mialon et al. in US patent no US 2013/0137847 A1. 2013 disclosed bio-renewable PET mimic derived from lignin-based aromatics. Caillol et al. in Green Chemistry, Volume 16, Page 1987, Journal 2014 reported a library of monomers starting from vanillin, which in turn is obtained from lignin.
Wadgaonkar et al. in European Polymer Journal, Volume 71, Page 547, Journal 2015 reported aliphatic-aromatic polyurethanes and in WO patent no WO 2015/140818 A1 disclosed pendant furyl containing bisphenols starting from lignin-based aromatics.
It would be advantageous to provide novel aromatic diisocyanates from bio-based starting materials. Such diisocyanates find applications in polyurethane industries.
Korean Pat. No. KR20130056025 discloses manufacturing method of polyurethane resin comprising the steps of 1) a mixture obtained by mixing poly(tetramethylene glycol)(PTMG), poly(carbonate diol), 1,3-propandiol, 1,4-butandiol, 2,2-bis(hydroxyl methyl) propionic acid(DMPA) as a diol/polyols and dibutyltin dilaurate(DBTDL) as a catalyst; 2) Prepolymer was synthesized by reaction of diisocyanate with mixture of diol/polyols and catalyst; 3) Polyurethane resin was synthesized by adding a chain extender into the prepolymer mixture. Chain extender was selected from EDA(ethylenediamine), DETA(diethylene tri amine).
Chinese Pat. No. CN103030969 discloses waterborne polyurethane curing agent and its preparation method. Polyurethane curing agent is made by using polyisocyanate (46-77%), polyether polyol (3.5-17.2%), phosphoric acid (01-0.05%), DBTDL (0.01-0.3%) and solvent such as N,N-dimethylformamide at a temperature of 65° C.-100° C. for 3-6 h.
Korean Pat. No. KR20030049684 discloses polymeric resin composition for water curable filler and process for producing polyurethane using the same composition. The process for producing polyurethane comprises the step of agitating polyisocyanate (mixed polyisocyanate containing MDI and isophorone diisocyanate in the ratio of 4:1) with the polymeric resin composition for water curable fillers in the ratio of 1:1 at a high speed. The polymeric resin composition for water curable fillers comprises 30 to 100 wt % of greeno13001, 0.1 to 5 wt % of TEDA, 5 to 30 wt % of DPG(1000, 750, 280), 0.1 to 5 wt % of DBTDL, 5 to 30 wt % of DMEA, 0.1 to 5 wt % of B8404, 1 to 10 wt % of H2O, 8 to 28 wt % of CaCO3, 1.4 to 8.5 wt % of 1,4-butanediol, 1.8 to 30 wt % of ethylene oxide, and 10 to 40 wt % of glycerol.
PCT Pat. Appl. No. WO2011123492 discloses a method of making polyurethane dispersions made from a mixture of aromatic polyisocyanates including: (1) forming a polyurethane prepolymer from a composition including: a) at least one polyol; b) at least one diol containing carboxyl functionality; c) an isomeric mixture of diphenylmethyl diisocyanate including about 37% by weight or less of 4,4′-methylene bis (phenyl isocyanate); and optionally, but desirably, d) at least one additional aromatic isocyanate and (2) combining the polyurethane prepolymer from step (1) with at least one neutralizing amine and water. DBTDL is also used.
Article titled “Preparation and characterization of waterborne polyurethane crosslinked by urea bridges” by Hercule et al. published in International Journal of Chemistry, 2011, 3 (2), pp 88-96 reports waterborne polyurethane dispersion were prepared by polyaddition reaction using polyethylene glycol (PEG Mw 2000) and isophorone diisocyanate (IPDI) in presence of dibutyltin dilaurate (DBTL) as catalyst.
Article titled “Catalytic activity of DBTDL in polyurethane formation” by Niyogi Sobhan et al. published in Indian Journal of Chemical Technology, 2002, 9, pp 330-333 reports preparation of Polyurethane from neopentyl glycol (NPG) and toluene diisocyanate (TDI) using dibutyltin dilaurate (DBTDL) catalyst.